HELP- Hens attacking new Phoenix rooster! double post! sorry

I just got my new rooster home today from Alycia. I put him in with my hens that are .5 a week younger than him, but he is much, much smaller. My hens keep doing a long "eewwwwww" hiss sound. When they get close to him they puff up and jump jump on his back and peck him. I am worried the will gang beat him to death. What do I do?